The radio frequency (RF) spectrum is a limited commodity. Only a small portion of the spectrum can be assigned to each communications industry. The assigned spectrum, therefore, must be used efficiently in order to allow as many frequency users as possible to have access to the spectrum. Multiple access modulation techniques are some of the most efficient techniques for utilizing the RF spectrum. Examples of such modulation techniques include time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA).
In order to attract and retain subscribers, wireless service provider frequently introduce end-user services that are desirable to consumers. These end-user services may include packet data services that enhance Internet service in wireless networks. There are two enhancements to the CDMA 2000 air interface: 1xEV-DO (defined by TIA IS-856) and 1xEV-DV (defined by TIA IS-2000-C). These new air interface standards enable high-speed packet data delivery to a mobile station to occur more efficiently and with higher data rates than currently available systems using CDMA2000 (also called 3G-1x). The two key improvements in the 1xEV-DV/DO protocol:
1) Instead of assigning a dedicated Supplemental Channel (SCH) to each user for packet data delivery, the 1xEV-DV/DO protocol uses a single-high speed Packet Data Channel (PDCH) that is shared between users. Under the 1xEV-DO protocol, user traffic is multiplexed onto the channel using Time Division Multiplexing (TDM). Under the 1xEV-DV protocol, user traffic may be multiplexed onto the channel using Time Division Multiplexing (TDM) and Code Division Multiplexing (CDM). This allows each user to receive the highest data rate available when they have access to the channel.
2) In the 1xEV-DV protocol, the mobile station indicates to the network which base station the mobile station wants to receive the data burst from. This is a change from 3G-1x, where the mobile sends Pilot Strength Measurement Messages to the network and the network chooses which base station to use for the data burst transmissions to the mobile station.
These changes require new functionality in wireless network base stations. Currently, in the 3G-1x system, users are allocated dedicated traffic channels by a source (or anchor) base station controller (BSC). A dedicated connection is established between the source BSC and any one or more target BSCs that are currently in the active set of the mobile station (as indicated to the source BSC by Pilot Strength Measurement messages transmitted by the mobile station). There is a separate connection for each dedicated traffic channel used by a subscriber. As data arrives at the source BSC for different users, the source BSC schedules traffic channel (e.g., supplemental Channel (SCH)) assignments between subscribers and sends the appropriate control signals to the target BSCs. Once the SCH(s) have been assigned, the source BSC forwards data to the appropriate target BSC.
The above-described centralized approach to distributing packet data traffic is time consuming and requires a large amount of control signaling between the source BSC and the target BSCs before data can actually be sent to the mobile station. Subscriber data rates are limited by the data rates of the dedicated traffic channels and the number of other users being served in the same sector.
There is therefore a need in the art for improved systems and methods for routing packet data between base stations in a wireless network. In particular, there is a need in the art for improved systems and methods for routing packet data between a source (or anchor) base station controller (BSC) and one or more target base station controllers. More particularly, there is a need for a packet data router that more efficiently transfers data packets between a source BSC and at least one target BSC.